Tubular shaft instruments of this type are used as surgical instruments in minimally invasive surgery in order to perform surgical interventions through a small body incision under endoscopic control. For various surgical procedures that are to be performed in the human or animal body, such tubular shaft instruments are equipped for various functions.
A tubular shaft instrument, in the sense of the present invention, is understood to mean, for example, a forceps for cutting and/or grasping and/or a needle holder. The jaw member arrangement can have a movable jaw member that interacts with a blade of a second jaw member that is fastened to the tube. The jaw member arrangement can also have blunted jaw members for gripping tissue. In the case of a needle holder, the jaw members are suited for removably holding a needle in order to produce a seam in the surgical area to mend tissue.
To activate the jaw member arrangement, there is on the proximal end of the tube a hand piece that has a force-locked connection with the movable jaw member by means of an elongated force transmission element, normally in the form of a pull rod. Manual actuation of the handles of the hand piece causes a movement of the jaw member arrangement on the distal end of the tube in order to perform the desired task such as, for example, cutting or holding tissue or guiding a needle through the tissue.
For minimally invasive surgery, especially in operating on small children or else with procedures in certain surgical areas such as the head area, it is also necessary to configure such tubular instruments with a very small tube diameter.
In addition, with tubular shaft instruments there is the requirement that they should be flushable with liquid lengthwise, in order to avoid the necessity of completely dismantling them. To provide the space necessary for flushing, it is proposed in the aforementioned state of the art to make the pull rod generally slightly thinner than the inner diameter of the tube, but in at least one section along their length to provide three supporting protrusions, distributed around the radius, that on the one hand would support the force transmission element centrally in the tube so that it cannot easily bend, and on the other hand would also allow free space in these sections for rinsing the tube in order to comply with sterility and hygienic requirements.